I. Field of the Invention
The present invention relates generally to transmissions and, more particularly, to a transmission for a vehicle such as a car or the like.
II. Description of the Prior Art
The previously known transmissions of the type used on cars, small trucks and the like, typically comprise a housing having a driven member which is coupled to and rotates in unison with the drive shaft from the engine. Similarly, these previously known transmissions include a drive member which is coupled to the drive train for the vehicle so that rotation of the drive member in one direction propels the car forwardly while the rotation of the drive member in the opposite direction propels the vehicle rearwardly. Conversely, the driven member rotates in a single and predetermined direction of rotation since it is coupled to the drive shaft from the engine.
These previously known vehicle transmissions are classified as either manual or automatic transmissions. In either case, however, a plurality of coupling members are provided within the transmission housing for drivingly connecting the transmission driven member to its drive member and thus for connecting the engine drive shaft to the vehicle drive train. In a manual transmission, the gear ratio between the transmission driven and drive members is controlled by the actuation of a gear shaft lever by the driver. In an automatic transmission, however, a hydraulic fluid is selectively provided to one or more fluid couplings and/or fluid brakes within the transmission housing to connect the driven member to drive member in different gear ratios.
A common automatic transmission employed in automotive vehicles is known as a single planetary, three speed transmission. This previously known automatic transmission uses three fluid couplings and two fluid brakes which are selectively actuated to produce three different gearing ratios between the transmission driven and drive members. The selection of the gearing ratio is carried out automatically by the transmission in dependence upon the engine speed and load conditions.
In order to obtain the reverse direction in an automatic transmission, however, it is necessary to add a plurality of additional coupling members to the automatic transmission. These additional coupling members not only significantly increase the overall cost of the automatic transmission and the weight of the transmission but also increase the axial length of the vehicle transmission. The additional axial length of the transmission is particularly disadvantageous in small or compact vehicles where the transmission length must be maintained at a minimum.